1. The Comma

2. What is the Comma?
The comma is a valuable, useful punctuation device because it separates the structural elements of sentences into manageable segments.
It is one of the most used, and often misused, forms of punctuation.

3. What is it used for? It is used to separate:
The elements in a series
Two independent clauses
It is also used to set off:
Introductory phrases
Non-essential elements

4. Separating Elements in a Series
The comma is used to separate three or more elements in a series. It creates a clearer sentence with less confusion.
I like to eat apples, oranges, and bananas.
The Constitution establishes the legislative, executive, and judicial branches of government.
The candidate promised to lower taxes, protect the environment, reduce crime, and end unemployment.

5. Separating two independent clauses.
It is important to use a comma to separate independent clauses when they are joined by any of these seven coordinating conjunctions: and, but, for, or, nor, so, yet.
He hit the ball, but he ran toward third base.
I like to play tennis with my friends, but I like to run by myself.
I want to go to the movies, and I want to go to dinner.

6. How the comma is used to set off introductory phrases.
Use commas after introductory a) clauses, b) phrases, or c) words that come before the main clause.
You can recognize introductory phrases by Common starter words such as, after, although, as, because, if, since, when, while. Also, Common introductory words, yes, however, well should be separated by a comma.
While I was eating, the doorbell rang.
Because her alarm clock was broken, she was late for class.
If you are sick, you should see a doctor.
When the rain stops coming down, we'll go play outside.
Well, perhaps he meant no harm.
Yes, I want to go on a date with you.
However, you may not be satisfied with the results.

7. Continued (introductory phrases)…
Commas should also be used to separate long prepositional phrases over 4 words.
Having finished eating, he left the table.
To get a seat, you'd better come early.
After the test, but before dinner, I went swimming.
The sun radiating intense heat, we sought shelter in the cafe.

8. Setting off Non-Essential Elements
A pair of commas, in the middle of a sentence, should be used to set off clauses, phrases, and words that are not essential to the meaning of the sentence.
These are three questions you should ask yourself to help you decided whether the sentence element is essential.
If you leave out the clause, phrase, or word, does the sentence still make sense?
Does the clause, phrase, or word interrupt the flow of words in the original sentence?
If you move the element to a different position in the sentence, does the sentence still make sense?
If you answer "yes" to one or more of these questions, then the element in question is nonessential and should be set off with commas

9. Continued (non-essential elements)…
Examples of sentences using commas to separate non-essential elements:
Clause: That Tuesday, which happens to be my birthday, is the only day when I am available to meet.
Phrase: This restaurant has an exciting atmosphere. The food, on the other hand, is rather bland.
Word: I appreciate your hard work. In this case, however, you seem to have over-exerted yourself.

10. When not to use the Comma
Don't use a comma to separate the subject from the verb.
An eighteen-year old in California, is now considered an adult. (incorrect)
An eighteen-year old in California is now considered an adult. (correct)
Don't put a comma between the two verbs or verb phrases in a compound predicate.
Don't put a comma between the two nouns, noun phrases, or noun clauses in a compound subject or compound object.
Don't put a comma after the main clause when a dependent (subordinate) clause follows it (except for cases of extreme contrast).
She was late for class, because her alarm clock was broken.(incorrect)
She was late for class because her alarm clock was broken, (correct)

11. Outside Sources Quiz on Comma Usage
In this quiz you will be given a paragraph and you have to change the sentences when needed
In this quiz you will be given sentences in which you have to choose the correct answer from 3 choices.

12. Contents Home What is the Comma? What is it used for?
Separating Elements in a Series
Separating two independent clauses
How the Comma is used to set off introductory phrases
Continued (introductory phrases)
Setting off non-essential elements
Continued (non-essential elements)
When not to use the Comma
Outside sources